Incidence conjecture for Klein's arrangements of lines and conics

Let GR(214)\mathrm{GR}(21_4) be the Grünbaum–Rigby configuration, decomposed into subconfigurations S12\mathrm S_{12}, S13\mathrm S_{13}, and S23\mathrm S_{23} with point orbits P1\mathrm P_1, P2\mathrm P_2, and P3\mathrm P_3. Let S12\mathrm S'_{12}, S13\mathrm S”_{13}, and S23\mathrm S”'_{23} be configurations isomorphic to these subconfigurations, with point sets P1,P2S12\mathrm P'_1,\mathrm P'_2\subset\mathrm S'_{12}, P1,P3S13\mathrm P”_1,\mathrm P”_3\subset\mathrm S”_{13}, and P2,P3S23\mathrm P”'_2,\mathrm P”'_3\subset\mathrm S”'_{23}. Suppose that the point sets P1\mathrm P'_1 and P2\mathrm P'_2 are inscribed in conics C1C_1 and C2C_2, respectively. Incidence conjecture. The configurations S12\mathrm S'_{12}, S13\mathrm S”_{13}, and S23\mathrm S”'_{23} can be chosen so that their union forms a configuration isomorphic to GR(214)\mathrm{GR}(21_4), with P1\mathrm P'_1 identified with P1\mathrm P”_1, P2\mathrm P'_2 identified with P2\mathrm P”'_2, and P3\mathrm P”_3 identified with P3\mathrm P”'_3; moreover, the common point set P3=P3\mathrm P”_3=\mathrm P”'_3 is inscribed in a conic C3C_3. This conjecture asserts that two prescribed conic incidences among the point orbits can be completed compatibly to the full Grünbaum–Rigby configuration, while the existence and geometric properties of the third conic remain the substantive issue.

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Primary source

Gábor Gévay and Piotr Pokora, “Klein's arrangements of lines and conics”, arXiv:2211.15309 (2023).

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